Before a planned trip to the U.S., Cheng wanted to get vaccinated against COVID-19. To do so, he asked a friend working at a cold-chain logistics company in southeast China to pretend he was employed by the firm, allowing Cheng access to one of the country’s experimental shots.

Cheng, a business owner from Beijing, now plans to fly to Guangdong province and pay as much as $91 to take two doses of what he believes is a vaccine being produced by a unit of Sinopharm, the state-backed Chinese developer at the front of the global COVID-19 vaccine race.

"You just transfer him the money via Alipay, but he won’t tell you the details because apparently it’s black market,” said Cheng, referring to a digital payments platform that’s used widely in China. Cheng asked to only be identified by his last name as he fears reprisal for speaking publicly.